Concrete low-speed corrosion device and method considering longitudinal load effect

Abstract

A concrete low-speed corrosion device considering a longitudinal load effect is characterized in that a to-be-tested concrete test piece is cylindrical, a first through hole is formed along the central axis of the to-be-tested concrete test piece, a spring, a spring clamping plate, an upper clamping plate and a lower clamping plate are respectively arranged on the top surface and the bottom surface of the to-be-tested concrete test piece to form a test body, and the water flow corrosion effect is simulated through autorotation of the test body; testing and calculating the relation between the spring compression amount and the axial pressure load borne by the test piece in advance to obtain the axial pressure load under different spring compression amounts; the top surface of the acrylic barrel is hermetically and fixedly connected with an upper cover plate, the upper cover plate and the acrylic barrel jointly form a cavity, a test body is arranged in the cavity, one end of a rotating rod penetrates through an upper clamping plate, extends into the cavity and then is fixedly connected with the test body, the other end of the rotating rod is positioned outside the closed cavity and is connected with a motor through a coupler, and the motor is connected with a frequency modulator. The invention further provides a concrete low-speed corrosion method considering the longitudinal load effect. The device can test the corrosion influence condition of different load effects on the concrete surface at a certain water flow velocity.

Description

Technical Field

[0001] The invention belongs to a concrete dissolution test method, and in particular relates to a concrete low-speed dissolution device and method taking longitudinal load action into consideration. Background Art

[0002] In mountain tunnels and underground projects, concrete structures are subjected to long-term water dissolution and surrounding rock longitudinal compressive loads, which causes surface wear, leading to degradation of concrete mechanical properties and shortened service life of the structure. Research on the water dissolution of concrete surface under different axial compressive loads and the water dissolution mechanism of concrete structure is of great significance for the durability design of concrete structure.

[0003] At present, the main methods for testing the water corrosion resistance of concrete are electrochemical acceleration method and chemical solution immersion acceleration method. CN108362594A discloses "Electrically Accelerated Concrete Corrosion Test Device and Method Simulating Bidirectional Tension and Pressure Action". Its test method is to control the bidirectional tension and pressure action of concrete specimens through a reaction frame, and use electrochemical methods to accelerate the corrosion experiment, only considering the concrete corrosion under static water. In the article "Mechanism of Deterioration of Medium-heated Portland Cement Paste under Corrosion Action", Ma Yuefeng used 5mol / L NH4Cl solution immersion to evaluate the corrosion resistance of concrete specimens. This method analyzes the influence of water flow corrosion on concrete specimens in natural environment by immersion in high-concentration solution and electrochemical acceleration of ion movement speed in solution. However, electrochemical acceleration will aggravate the erosion of concrete by ions. CN201911087332.7 discloses "Erosion device and method for testing shear stress of concrete surface under water flow", and its experimental method is to simulate water flow erosion by rotating the test body, which is convenient for directly obtaining the erosion strength of the surface of the concrete specimen to be tested, but has not yet considered the water erosion corrosion of the concrete surface under load. In summary, it can be seen that the existing methods cannot obtain the erosion of the concrete surface under load by natural water flow, nor can they establish a quantitative relationship between load and concrete erosion degree (such as quality, strength, etc.). Summary of the invention

[0004] In order to overcome the shortcomings of the existing technology, the present invention provides a low-speed concrete dissolution device and method taking into account the longitudinal load effect, which can test the dissolution effect of different loads on the concrete surface under a certain water flow rate and establish the relationship between the axial compressive load and the dissolution quality.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] A low-speed concrete dissolution device considering the longitudinal load effect comprises an upper cover plate, an acrylic barrel, a screw, a spring, a spring clamp, a rotating rod, an upper clamp plate, a lower clamp plate, a motor and a frequency regulator; the concrete specimen to be tested is cylindrical, and a first through hole is opened along its central axis; the spring, the spring clamp plate, the upper clamp plate and the lower clamp plate are respectively arranged on the top surface and the bottom surface of the concrete specimen to be tested to form a test body, and the water flow dissolution effect is simulated by the rotation of the test body, and the axial compressive load under different spring compressions is obtained by testing and calculating the relationship between the spring compression amount and the axial compressive load on the specimen in advance; the top surface of the acrylic barrel is sealed and fixedly connected to the upper cover plate, and the upper cover plate and the acrylic barrel together form a cavity, and the test body is arranged in the cavity, one end of the rotating rod passes through the upper clamp plate and extends into the cavity and is fixedly connected to the test body, and the other end of the rotating rod is located outside the closed cavity and is connected to the motor through a coupling, and the motor is connected to the frequency regulator.

[0007] Furthermore, the centers of the upper cover plate, the acrylic barrel, the upper clamping plate, the lower clamping plate, the spring, the spring clamp and the concrete specimen to be tested are all on the same axis.

[0008] Furthermore, a ball bearing is provided at the center of the top surface of the upper cover plate, and a second through hole is opened from the top surface of the ball bearing to the top surface of the upper cover plate, and the rotating rod passes through the second through hole and extends into the cavity. In this solution, the ball bearing forms a lateral support to prevent the rotating rod from swinging too much during rotation.

[0009] The upper clamping plate and the lower clamping plate are both circular plates, and the centers of the plates are respectively provided with third through holes.

[0010] Furthermore, the rotating rod is composed of a first cylinder, a second cylinder and a third cylinder from top to bottom, the first cylinder is connected to a motor via a coupling, the diameter of the second cylinder is larger than the diameter of the third cylinder, and threads are respectively provided at both ends of the third cylinder. After the third cylinder passes through the through hole of the test body, its bottom is fixed to the lower clamping plate by a nut, and the top of the third cylinder is connected to the spring, the spring clamping plate and the upper clamping plate by threads, and the threaded surfaces of the second cylinder and the third cylinder are used to limit the spring clamping plate.

[0011] A method for low-speed dissolution of concrete taking into account the effect of longitudinal load, the method comprising the following steps:

[0012] Step 1, the concrete specimen to be tested is cylindrical, with a radius of r, a height of H, and a density of ρ; a first through hole is opened in the center of the concrete specimen to be tested, its mass is weighed, m0 is recorded, and the porosity P0 of the concrete specimen to be tested is measured by the drainage weighing method;

[0013] Step 2: Calculate the axial compressive load exerted by the spring and the upper clamping plate on the concrete specimen:

[0014] Step 3: Calculate the spring stiffness coefficient:

[0015] Step 4: Calculate the longitudinal compressive load F=F0+kL on the upper and lower bottom surfaces of the concrete specimen under the spring compression;

[0016] Step 5. While keeping the spring compression L unchanged, add water to the acrylic barrel, adjust the frequency converter to control the motor rotation, record the value R1 displayed on the frequency converter display at a certain speed, maintain a certain uniform low speed for a certain period of time, remove the concrete specimen to be tested, wipe off the surface moisture, weigh its mass, and record it as m1;

[0017] Step 6: Measure the porosity P1 of the concrete specimen by drainage weighing method

[0018] Step 7, continue to install the concrete specimen to be tested on the rotating rod, and fix it by means of the spring, the spring clamp, the upper clamp and the lower clamp, adjust the frequency converter to keep the motor speed unchanged, and record the value R2 displayed by the frequency converter at the speed to keep it the same as the speed value during the entire experimental stage;

[0019] Step 8: After a certain period of dissolution, remove the concrete specimen to be tested, wipe off the surface moisture, weigh its mass, and record it as m2;

[0020] Step 9, measuring the porosity P2 of the concrete specimen to be tested by the drainage weighing method;

[0021] Step 10, repeating steps 5 to 9, the water flow erosion effect at different speeds on the surface of the concrete specimen under different axial compressive loads can be obtained, and then a quantitative relationship between load action, water erosion intensity and concrete compressive strength, quality and porosity can be established.

[0022] Preferably, in step 2, the spring and the spring clamp are fixed on the rotating rod, the rotating rod and the motor are connected with a coupling so that they are located on the same axis, and the spring clamp and the upper and lower clamps are tightened with a nut; a dynamometer is placed between the upper and lower clamps, and when the spring maintains its original length, the compressive load of the spring on the upper clamp is the self-weight of the spring clamp and the self-weight of the spring, and the value F0 measured by the dynamometer is the sum of the self-weight of the spring clamp, the self-weight of the spring and the self-weight of the upper clamp, and the spring clamp nut is rotated to compress the spring, and the value F measured by the dynamometer is the sum of the self-weight of the spring clamp, the self-weight of the spring, the self-weight of the upper clamp and the reaction force after the spring is compressed.

[0023] More preferably, in step 3, the spring, spring clamp, upper clamp, dynamometer and lower clamp are installed on the rotating rod: the spring clamp nut is tightened at a uniform speed, the dynamometer reading is observed, and the axial compressive load value F generated by the spring under different compression amounts L is recorded. Therefore, the axial compressive load generated by the spring on the concrete specimen is measured to be F=F0+kL. Through multiple tests, the spring stiffness coefficient k=(F-F0) / L is obtained.

[0024] The beneficial effects of the present invention are mainly manifested in: 1. Through the combination of the spring and the upper clamping plate, a uniform and stable axial compressive load is formed on the concrete specimen to be tested, and the size of the axial compressive load on the specimen can be directly obtained; 2. The rotation of the motor is controlled by the frequency regulator, which is convenient for control and has high precision; 3. By applying a uniform and stable axial compressive load, cooperating with the motor to drive the concrete specimen to rotate to form a water flow effect, a quantitative relationship between the load effect, water dissolution strength and the compressive strength, quality and porosity of concrete can be established. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the structure of the concrete low-speed dissolution device considering the longitudinal load.

[0026] Figure 2 It is a schematic diagram of the upper cover plate of the present invention.

[0027] Figure 3 It is a schematic diagram of an acrylic bucket of the present invention.

[0028] Figure 4 It is a schematic diagram of a splint of the present invention.

[0029] Figure 5 Schematic diagram of the rotating rod of the present invention.

[0030] Figure 6 It is a schematic diagram of a steel spring of the present invention.

[0031] Figure 7 The figure is a flow chart of a method for low-rate dissolution of concrete considering the effect of longitudinal load. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with the accompanying drawings.

[0033] Reference Figure 1 to Figure 6A low-speed concrete dissolution device considering the longitudinal load includes an upper cover plate 2, an acrylic barrel 1, a spring 9, a spring pressure plate 10, a rotating rod 5, an upper clamping plate 7, a lower clamping plate 8, a motor 11 and a frequency modulator 12. The concrete specimen 6 to be tested is cylindrical and has a first through hole along its central axis. The spring 9, the spring pressure plate 10, the upper clamping plate 7 and the lower clamping plate 8 are respectively arranged on the top and bottom surfaces of the concrete specimen 6 to be tested to form a test body. The water flow dissolution effect is simulated by the self-rotation of the test body so as to obtain its surface Surface dissolution strength; the top surface of the acrylic bucket 1 is sealed and fixedly connected to the upper cover plate 2 by bolts, and the upper cover plate 2 and the acrylic bucket 1 together constitute a cavity, the test body is set in the cavity, and the cavity is filled with water, one end of the rotating rod 5 passes through the upper clamping plate 7 and extends into the cavity and is fixedly connected to the test body, the other end of the rotating rod 5 is located outside the closed cavity and is connected to the motor 11 through a coupling, the motor 11 is connected to the frequency modulator 12, the frequency modulator 12 controls the rotation of the motor 11, and the application of the frequency modulator 12 is convenient for controlling the speed of the motor 12 with high accuracy.

[0034] The centers of the upper cover plate 2, the acrylic barrel 1, the upper clamping plate 7, the lower clamping plate 8, the spring 9, the spring clamping plate 10 and the concrete specimen 6 to be tested are all on the same axis.

[0035] A ball bearing is provided at the center of the top surface of the upper cover plate 2, and a second through hole is opened from the top surface of the ball bearing to the top surface of the upper cover plate 3. The rotating rod 5 extends into the cavity through the second through hole. The ball bearing forms a lateral support to prevent the rotating rod 5 from swinging too much during rotation.

[0036] The upper clamping plate 7 and the lower clamping plate 8 are both circular plates, and a third through hole is respectively provided at the center thereof.

[0037] The rotating rod 5 is made of stainless steel and consists of a first cylinder, a second cylinder and a third cylinder from top to bottom. The first cylinder is connected to the motor 11 through a coupling. The diameter of the second cylinder is larger than the diameter of the third cylinder. Both ends of the third cylinder are provided with threads. After the third cylinder passes through the through hole of the test body, its bottom is fixed to the lower clamping plate 8 by a nut. The top of the third cylinder is connected to the upper clamping plate 7 by a thread. The threaded surfaces of the second cylinder and the third cylinder are used to limit the spring clamping plate (10).

[0038] Reference Figure 7 A method for low-speed dissolution of concrete considering longitudinal loads comprises the following steps:

[0039] Step 1: The radius of the concrete specimen 6 to be tested is r, the height is H, and the density is ρ. A first through hole is opened in the center of the concrete specimen 6 to be tested, and its mass is weighed and recorded as m0;

[0040] Step 2: Calculate the axial compressive load generated by the spring 9 and the upper clamping plate 7 on the concrete specimen 6. The process is as follows:

[0041] Fix the spring 9 and the spring clamp 10 on the rotating rod 5, connect the rotating rod 5 and the motor 11 with a coupling so that they are located on the same axis, and tighten the spring clamp and the upper and lower clamps with a nut; take a dynamometer and place it between the upper and lower clamps. When the spring maintains its original length, the compressive load of the spring on the upper clamp is the deadweight of the spring clamp and the deadweight of the spring. The value F0 measured by the dynamometer is the sum of the deadweight of the spring clamp, the deadweight of the spring and the deadweight of the upper clamp. Rotate the spring clamp nut to compress the spring. The value F measured by the dynamometer is the sum of the deadweight of the spring clamp, the deadweight of the spring, the deadweight of the upper clamp and the reaction force after the spring is compressed;

[0042] Step 3: Calculate the spring stiffness coefficient. The process is as follows:

[0043] Install the spring 9, spring clamp 10, upper clamp 7, dynamometer and lower clamp 8 to the rotating rod 5: tighten the spring clamp nut at a uniform speed, observe the dynamometer reading, and record the axial compressive load value F generated by the spring under different compression amounts L. Therefore, the axial compressive load generated by the spring on the concrete specimen is measured to be F=F0+kL. Through multiple tests, the spring stiffness coefficient k=(F-F0) / L is obtained;

[0044] Step 4, calculate the longitudinal compressive load F=F0+kL on the upper and lower bottom surfaces of the concrete specimen 6 to be tested under the spring compression amount;

[0045] Step 5, while keeping the spring compression amount L unchanged, add water into the acrylic barrel 1, adjust the frequency converter 12 to control the motor 11 to rotate, record the value R1 displayed by the frequency converter 12 at a certain speed, maintain a certain uniform low speed for a certain period of time, remove the concrete specimen 6 to be tested, wipe off the surface moisture, weigh its mass, and record it as m1;

[0046] Step 6, measuring the porosity P1 of the concrete specimen 6 by a drainage weighing method;

[0047] Step 7, continue to install the concrete specimen 6 to be tested on the rotating rod 5, and fix it by means of the spring 9, the spring clamp 10, the upper clamp 7 and the lower clamp 8, adjust the frequency regulator 12, keep the speed of the motor 11 unchanged, record the value R2 displayed by the frequency regulator 12 at this speed and keep it the same as the torque value in the entire experimental stage;

[0048] Step 8: After the dissolution has lasted for a certain period of time, remove the concrete specimen 6 to be tested, wipe off the surface moisture, weigh its mass, and record it as m2;

[0049] Step 9: Measure the porosity P2 of the concrete specimen 6 by the drainage weighing method.

[0050] Step 10, repeating steps 5 to 9, the water flow erosion effect at different speeds on the surface of the concrete specimen 6 to be tested can be obtained under different axial compressive loads, and then a quantitative relationship between load action, water erosion strength and concrete compressive strength, quality and porosity can be established.

[0051] The contents described in the embodiments of this specification are merely enumerations of implementation forms of the inventive concept and are for illustrative purposes only. The protection scope of the present invention should not be considered to be limited to the specific forms described in this embodiment, and the protection scope of the present invention also extends to equivalent technical means that can be thought of by ordinary technicians in this field based on the inventive concept.

Claims

1. A low-speed concrete dissolution device considering the longitudinal load, characterized in that: The device comprises an upper cover plate, an acrylic barrel, a screw, a spring, a spring clamp, a rotating rod, an upper clamp, a lower clamp, a motor and a frequency regulator; the concrete specimen to be tested is cylindrical, and a first through hole is opened along its central axis; the spring, the spring clamp, the upper clamp and the lower clamp are respectively arranged on the top surface and the bottom surface of the concrete specimen to be tested to form a test body; the water flow erosion effect is simulated by the rotation of the test body; the axial compressive load under different spring compressions is obtained by calculating the relationship between the spring compression and the axial compressive load on the specimen through advance testing; the top surface of the acrylic barrel is sealed and fixedly connected to the upper cover plate, the upper cover plate and the acrylic barrel together form a cavity, the test body is arranged in the cavity, one end of the rotating rod passes through the upper clamp and extends into the cavity and is fixedly connected to the test body, the other end of the rotating rod is located outside the closed cavity and is connected to the motor through a coupling, and the motor is connected to the frequency regulator.

2. A low-speed concrete dissolution device considering longitudinal load as claimed in claim 1, characterized in that: The centers of the upper cover plate, the acrylic barrel, the upper clamping plate, the lower clamping plate, the spring, the spring clamp and the concrete specimen to be tested are all on the same axis.

3. A low-speed concrete dissolution device considering longitudinal load as claimed in claim 1 or 2, characterized in that: A ball bearing is arranged at the center of the top surface of the upper cover plate, a second through hole is opened from the top surface of the ball bearing to the top surface of the upper cover plate, and the rotating rod passes through the second through hole and extends into the cavity.

4. A low-speed concrete dissolution device considering longitudinal load as claimed in claim 3, characterized in that: The upper clamping plate and the lower clamping plate are both circular plates, and the centers of the plates are respectively provided with third through holes.

5. A low-speed concrete dissolution device considering longitudinal load as claimed in claim 1 or 2, characterized in that: The rotating rod is composed of a first cylinder, a second cylinder and a third cylinder from top to bottom. The first cylinder is connected to a motor via a coupling. The diameter of the second cylinder is larger than the diameter of the third cylinder. Both ends of the third cylinder are provided with threads. After the third cylinder passes through the through hole of the test body, its bottom is fixed to the lower clamping plate by a nut. The top of the third cylinder is connected to the spring, the spring clamping plate and the upper clamping plate by threads. The threaded surfaces of the second cylinder and the third cylinder are used to limit the spring clamping plate.

6. A method for implementing the low-speed concrete dissolution device considering longitudinal load as claimed in claim 1, characterized in that: The method comprises the following steps: Step 1, the concrete specimen to be tested is cylindrical, with a radius of r, a height of H, and a density of ρ; a first through hole is opened in the center of the concrete specimen to be tested, its mass is weighed, m0 is recorded, and the porosity P0 of the concrete specimen to be tested is measured by the drainage weighing method; Step 2: Calculate the axial compressive load exerted by the spring and the upper clamping plate on the concrete specimen: Step 3: Calculate the spring stiffness coefficient: Step 4: Calculate the longitudinal compressive load F=F0+kL on the upper and lower bottom surfaces of the concrete specimen under the spring compression; Step 5. While keeping the spring compression L unchanged, add water to the acrylic barrel, adjust the frequency converter to control the motor rotation, record the value R1 displayed on the frequency converter display at a certain speed, maintain a certain uniform low speed for a certain period of time, remove the concrete specimen to be tested, wipe off the surface moisture, weigh its mass, and record it as m1; Step 6: Measure the porosity P1 of the concrete specimen by drainage weighing method Step 7, continue to install the concrete specimen to be tested on the rotating rod, and fix it by means of the spring, the spring clamp, the upper clamp and the lower clamp, adjust the frequency converter to keep the motor speed unchanged, and record the value R2 displayed by the frequency converter at the speed to keep it the same as the speed value during the entire experimental stage; Step 8: After a certain period of dissolution, remove the concrete specimen to be tested, wipe off the surface moisture, weigh its mass, and record it as m2; Step 9, measuring the porosity P2 of the concrete specimen to be tested by the drainage weighing method; Step 10, repeating steps 5 to 9, the water flow erosion effect at different speeds on the surface of the concrete specimen under different axial compressive loads can be obtained, and then a quantitative relationship between load action, water erosion intensity and concrete compressive strength, quality and porosity can be established.

7. The method according to claim 6, characterized in that In the step 2, the spring and the spring clamp are fixed on the rotating rod, the rotating rod and the motor are connected with a coupling so that they are located on the same axis, and the spring clamp and the upper and lower clamps are tightened with a nut; a dynamometer is placed between the upper and lower clamps, and when the spring maintains its original length, the compressive load of the spring on the upper clamp is the self-weight of the spring clamp and the self-weight of the spring, and the value F0 measured by the dynamometer is the sum of the self-weight of the spring clamp, the self-weight of the spring and the self-weight of the upper clamp, and the spring clamp nut is rotated to compress the spring, and the value F measured by the dynamometer is the sum of the self-weight of the spring clamp, the self-weight of the spring, the self-weight of the upper clamp and the reaction force after the spring is compressed.

8. The method according to claim 6 or 7, characterized in that In step 3, the spring, spring clamp, upper clamp, dynamometer and lower clamp are installed on the rotating rod: the spring clamp nut is tightened at a uniform speed, the dynamometer reading is observed, and the axial compressive load value F generated by the spring under different compression amounts L is recorded. Therefore, the axial compressive load generated by the spring on the concrete specimen is measured to be F=F0+kL. Through multiple tests, the spring stiffness coefficient k=(F-F0) / L is obtained.

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